Display devices used in equipment such as computers or mobile telephones are used to display sets of data. Such sets of data in the form of documents, web pages or program menus are often too large for the whole set to be displayed on the display device at any given time. Display devices therefore provide controls in the form of scroll bars or specialised keys on an associated keyboard to allow input of user commands to change the portion of the set of data being displayed. These user commands enable a user to move through or navigate the set of data. The commands commonly enable a user to navigate a set of data incrementally by line, paragraph, or page, or to jump to the start or the end of the set of data. Some application programs provide search facilities which enable automatic navigation to each successive occurrence of a search term.
When a user has carried out one or more navigation steps, a return to a previously displayed position in the set of data can be affected by further user commands which effectively reverse the original navigation steps. However, such a procedure is both time consuming and awkward. Some application programs enable a user to manually log return positions or bookmarks in a set of data which can be returned to using specific user commands. Other application programs are arranged to enter such return positions or bookmarks automatically at points in a set of data which are viewed for a time exceeding a predetermined threshold. One problem with the automatic insertion of return positions based on a time threshold is that it assumes that a users attention is evenly applied to set of data being displayed. If, for example, the user is distracted from the display device for longer than the predetermined threshold and part-way through scrolling though a document, then a return point would be logged at the point. Such a return point may be unwanted. In other words, return points in such a system do not necessarily reflect significant points in a user's navigation of the set of data.